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Subject[tip:x86/irq] x86/dumpstack: Fix off-by-one errors in stack identification
Commit-ID:  fa33215422fd415a07ec2a00e9f1acdaf0fa8e94
Gitweb: https://git.kernel.org/tip/fa33215422fd415a07ec2a00e9f1acdaf0fa8e94
Author: Andy Lutomirski <luto@kernel.org>
AuthorDate: Sun, 14 Apr 2019 17:59:39 +0200
Committer: Borislav Petkov <bp@suse.de>
CommitDate: Wed, 17 Apr 2019 12:26:50 +0200

x86/dumpstack: Fix off-by-one errors in stack identification

The get_stack_info() function is off-by-one when checking whether an
address is on a IRQ stack or a IST stack. This prevents an overflowed
IRQ or IST stack from being dumped properly.

[ tglx: Do the same for 32-bit ]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190414160143.785651055@linutronix.de
---
arch/x86/kernel/dumpstack_32.c | 4 ++--
arch/x86/kernel/dumpstack_64.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index cd53f3030e40..d305440ebe9c 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -41,7 +41,7 @@ static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info)
* This is a software stack, so 'end' can be a valid stack pointer.
* It just means the stack is empty.
*/
- if (stack <= begin || stack > end)
+ if (stack < begin || stack > end)
return false;

info->type = STACK_TYPE_IRQ;
@@ -66,7 +66,7 @@ static bool in_softirq_stack(unsigned long *stack, struct stack_info *info)
* This is a software stack, so 'end' can be a valid stack pointer.
* It just means the stack is empty.
*/
- if (stack <= begin || stack > end)
+ if (stack < begin || stack > end)
return false;

info->type = STACK_TYPE_SOFTIRQ;
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 5cdb9e84da57..90f0fa88cbb3 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -65,7 +65,7 @@ static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
begin = end - (exception_stack_sizes[k] / sizeof(long));
regs = (struct pt_regs *)end - 1;

- if (stack <= begin || stack >= end)
+ if (stack < begin || stack >= end)
continue;

info->type = STACK_TYPE_EXCEPTION + k;
@@ -88,7 +88,7 @@ static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
* This is a software stack, so 'end' can be a valid stack pointer.
* It just means the stack is empty.
*/
- if (stack <= begin || stack > end)
+ if (stack < begin || stack >= end)
return false;

info->type = STACK_TYPE_IRQ;
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